Newly Discovered Brown Fat Activator May Advance Obesity Treatment

The results of a new study published in Cell Metabolism by the University of Copenhagen found that beta2-adrenergic receptors in brown fat cells are responsible for activation, which is the same receptor responsible for releasing fat from unhealthy white adipose tissue.?? The discovery of this switch could lead to targeted treatments for obesity and related conditions.

Brown fat, which humans have in small amounts, is activated by cold temperatures or chemical signals, and when it's turned on—a process called thermogenesis—it becomes like a personal furnace to generate heat and is fueled by the burning of calories.??

The findings of this study may also improve insulin sensitivity and affect appetite regulation, according to study co-author Camilla Schéele at the Noro Nordisk Foundation Center for Basic Metabolic Research. “Our data reveal a previously unknown key to unlocking these functions in humans, which would potentially be of great gain for people living with obesity or type 2 diabetes.”

Search for the Brown Fat Switch

Research on brown fat, also called brown adipose tissue or BAT, has been fairly recent but has generated tremendous interest, given its promise for changing body composition.

However, being able to harness the calorie-burning process associated with BAT has been a major question. One recent study published by the Nutrition and Toxicology Research Institute at Maastricht University in The Netherlands noted that even though cold has been confirmed as an activation switch, it's not a practical approach for treatment.

"Although cold exposure is undoubtedly the most physiological and effective regimen to activate and recruit BAT, it would be difficult and uncomfortable to increase human exposure to cold temperatures under well-controlled conditions with the presence of clothing and heating systems," researchers wrote in the study. "Moreover, chronic cold exposure increases blood pressure and may induce atherosclerosis."??

The commercial sector remains undeterred, though, and the search for a way to turn on thermogenesis has led to a mini-boom in thermogenic supplements that claim to increase fat burning and boost metabolism. Most often, key ingredients are those studied for potential thermogenic effects, such as caffeine, green tea, garcinia cambogia, and capsaicin.

There is some evidence that ingredients like these have a calorie-burning effect to some degree, but there are plenty of caveats to go with those claims. For example, one study found that every milligram of caffeine consumed in a 24-hour period helps burn an additional 0.1 calories.??

That means if you have three espressos—each with 63mg of caffeine—you'd burn an extra 18.9 calories in a day. For reference, that's just under half of a single Oreo cookie.

With the new research, discovering the specific receptor could be a major pivot point, especially since it's an unlikely switch. Beta2-adrenergic receptors, also known as ADRB2, are best known for their role in respiratory function, particularly related to relaxing muscles for bronchodilation. They have been associated with other functions, however, related to circulation, eye health, and digestion.

In a statement about the results, researcher Denis Blondin, MD, from Centre de recherche du Centre hospitalier universitaire de Sherbrooke said, "We show that perhaps we were aiming for the wrong target all along."

The Challenge of Obesity

Although treatment options based on the recent brown fat research are certainly not imminent—it would take years, if not close to a decade, to develop a drug that's ready for market—it's still important to keep moving in this direction, given the significant impact of obesity.

The condition has been linked to numerous health issues that go beyond diabetes and cardiovascular disease which include malnutrition, Alzheimers, depression, osteoarthritis, and complications due to COVID-19.?? Because of this, it's often associated with earlier mortality compared to those who are not obese.

Compounding the obesity issue is that once established, obesity is difficult to reverse, despite the claims of the U.S. weight-loss industry, estimated at about $72 billion.

"Unfortunately, what we see is that when the body becomes obese, it doesn't like to let go of that, no matter what goals an individual might set," says Erica Kenney, ScD, MPH, in the Department of Nutrition at the Harvard T.H. Chan School of Public Health.

"Investigating possible treatments is important, but we also need to put a great many more resources into prevention, on an individual level but also as a society," says Kenney. "We need to keep looking at why this problem is happening, why it's growing, and how we can break the cycle."